Micromys Dehne 1841

Wilson, Don E. & Reeder, DeeAnn, 2005, Order Rodentia - Family Muridae, Mammal Species of the World: a Taxonomic and Geographic Reference (3 rd Edition), Volume 2, Baltimore: The Johns Hopkins University Press, pp. 1189-1531 : 1383

Micromys Dehne 1841

Micromys Dehne 1841 , Micromys agilis, Ein Neues Saugetier der Fauna von Dresden : 1.

Type Species: Micromys agilis Dehne 1841

Species and subspecies: 1 species:

Species Micromys minutus ( Pallas 1771)

Discussion: Micromys Division. Generic diagnosis based upon molar traits provided by Storch (1987). Molar morphology indicates a close relationship with members of Misonne’s (1969) Progonomys group (within a more inclusive Lenothrix-Parapodemus Division), and phylogenetic relationships assessed by microcomplement fixation of albumin ( Watts and Baverstock, 1995 b) pointed to the Asian Vandeleuria (also a member of Misonne’s Progonomys cluster) as the closest living relative of Micromys , an alliance hinted at by Jüdes’s (1981) interpretation of chromosomal data, and explicitly indicated by Ellerman (1949:132) based upon morphology. Phylogenetic analyses of complete mtDNA cytochrome b sequences by Martin et al. (2000) could not resolve the phylogenetic position of Micromys relative to other murines and deomyines sampled ( Apodemus , Mus , Rattus , Acomys ), nor could analyses of sequences from the nuclear LCAT ( Robinson et al., 1997); neither of these studies included Vandeleuria . Micromys possesses a quality of the Lx family of long interspersed repeated DNA compared with other extant murines sampled ( Mus , Praomys , Rattus , Bandicota , Arvicanthis , Mastomys , Hylomyscus , Aethomys , Dasymys , and Apodemus ) that indicates it to be the most divergent of those genera and an outgroup to them ( Furano et al., 1994). Those authors speculated that Micromys diverged early from the core murine lineage, an observation consistent with scnDNA hybridization data ( Catzeflis et al., 1992), analyses of sequences from nuclear IRBP gene, and mtDNA cytochrome b and 12S rRNA ( Michaux et al., 2002 a), and the early presence of the genus and phylogenetic history in the Neogene. Micromys may have been the first lineage to have diverged from a common ancestral Progonomys like form approximately 12 million years ago ( Furano et al., 1994). Based upon her cladistic analysis of molar traits, Chaimanee (1998) suggested the Indomalayan Vandeleuria , Lenothrix , and Pithecheir are also members of this primary divergent lineage.

The early evolutionary origin of Micromys is reflected in its phylogenetic history documented by fossils representing ten extinct species: one from the late Miocene of Nei Mongol ( Storch, 1987), seven from the late Miocene, Pliocene, and Pleistocene of Europe, one of which occurs in Europe and Nei Mongol ( Qiu and Storch, 2000; Weerd, 1979; see Storch and Dahlmann, 1995, who reviewed all the fossil species of Micromys ), one from the early to late Pliocene of S China ( Cai and Qiu, 1993; Wu and Flynn, 1992), and another from the early Pleistocene of S China ( Zheng, 1993). "The fossil Micromys species do not represent a single lineage which finally leads to the living M. minutus .... the genus underwent radiations and shows a rather complex phylogenetic history" ( Storch and Dahlmann, 1995:128). Only one living species is recognized by most workers, but whether extant samples represent one or more species has yet to be resolved by critical systematic revision .